The UMC Cup is a Taiwanese professional tournament established in 2020.
It's organised by the Taiwan Qiyuan Culture Foundation and named after its sponsor, the United Microelectronics Corporation.
The tournament format appears to be quite intricate, with preliminaries, an eight player league and decision matches. The end result, though is that the finalists play a best of seven match. For more information, see the Go to Everyone! section.
2nd, 2021: Wang Yuanjun (now the Taiwan Tianyuan) d. Lai Junfu 4-2.
This was a more balanced match, even though the score margin was the same as the first. Whereas the first encounter had seen only resignation results, this time Wang won two close games at 1.5 and 2.5. Also, instead of a long streak taking place, Wang won only two games in a row, after which victories alternated.
Lu lost the demotion match to Xiao and was replaced by Xu Haohong.
 No information is apparently available about Lu Yuchuan. There are similarly named Chinese professionals Li Yuchuan (who died in early 2020) and Liu Yuncheng, but the most likely Taiwanese candidate seems to be Lu Yuhua (盧鈺樺). In that case, the reading or spelling of 樺 would be the source of the confusion. The difference between pinyin and Wade-Giles or other Taiwanese romanisation systems could also be a factor.
There's apparently also a knockout tournament, ending in a best of three match.
The knockout is sectioned separately on Go to Everyone!, as UMC Cup (tournament), with the league being the "UMC Cup".